Bioassay

Organic chemistry

Combinatorial chemistry

Alternaria solani

Thioether

Bacteria

Stereochemistry

Biology

Gene

Chemistry

Moiety

In vitro

Xanthomonas oryzae

Pyridine

Antibacterial activity

Quinazoline

Botany

EC50

Antimicrobial

Genetics

Biochemistry

Fungicide

Journal of Agricultural and Food Chemistry

A total of 22 quinazoline thioether derivatives incorporating a 1,2,4-triazolo[4,3-a]pyridine moiety were designed, synthesized, and evaluated as antimicrobial agents in agriculture. Among these compounds, the chemical structure of compound 6l was further confirmed via single-crystal X-ray diffraction analysis. The bioassay results revealed that some of the compounds possessed noticeable in vitro antibacterial activities against the tested phytopathogenic bacteria. For example, compounds 6b and 6g had EC50 values as low as 10.0 and 24.7 μg/mL against Xanthomonas axonopodis pv. citri (Xac), respectively, which were significantly better than that of the commercial agrobactericide bismerthiazol (56.9 μg/mL). Particularly, compound 6b was also found to be capable of suppressing the pathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo) approximately 12-fold more potent than control bismerthiazol, in terms of their EC50 values (7.2 versus 89.8 μg/mL). Importantly, the most active compound 6b turned out to be one with the highest hydrophilicity and the lowest molecular weight within the series. In vivo bioassays further showed the application prospect of 6b as a promising plant bactericide for controlling Xoo. Additionally, in vitro antifungal activities of these compounds were also evaluated at the concentration of 50 μg/mL. Overall, the present study demonstrated the potential of 1,2,4-triazolo[4,3-a]pyridine-bearing quinazoline thioether derivatives as efficient agricultural antibacterial agents for crop protection.

Synthesis, Crystal Structure, and Agricultural Antimicrobial Evaluation of Novel Quinazoline Thioether Derivatives Incorporating the 1,2,4-Triazolo[4,3-<i>a</i>]pyridine Moiety

Synthesis, Crystal Structure, and Agricultural Antimicrobial Evaluation of Novel Quinazoline Thioether Derivatives Incorporating the 1,2,4-Triazolo[4,3-a]pyridine Moiety